Pyrometer



l. LUNDGAARD May 15, N923.

PYROMETEVR Filed April 28 1921 Patented May l5, 1.923.

i' intatta raar. este PYROIIIETER.

Application filed April 28, 1921. Serial 4No..465,313.

To all whom t may concern:

Be it knownthat I, IvAR LUNDGVAARD, a citizen of the United States,residing at Rochester, in the county of Monroe and State of New York,have invented certain new anduseful Improvements in yPyrometers; and Ido hereby declare the following to be a full, clear, and exactdescription of the invention such as will enable others skilled in theart to which it appertains, to malre and use the same.

This invention relates particularly to the measurement and control ofcomparatively high temperatureasuch as those of furnaces, tho notessentially limited thereto.

'Ihe'object of the invention is to produce a. pyrometric device ofsimple and rugged construction, in which a sufficient degree of accuracymay be secured without recourse to delicate electric or otherinstrumentalities.

To the foregoing endI make use o f the principle that a given quantityof air or other gas, forced through an orifice of delinite size in agiven time, will create a baclpressure varying with changes in theteinperature of the air. While I do not claim this principle broadly asnovel, the present invention relates to improved means for utilizing it,these means being so constructed and arranged as to eliminate thenecessity for exact regulation of either the quantity of air forcedthrough the orifice o r the degree of pressure or force used to impelvthe air.

I accomplish the foregoing result by an arrangement in which theresponsive or indicating device is subjected to the differential eifectof the pressures in two chambers, one being the pyrometric chamber inwhich the air is subjected to the temperature which is to be measured,while the other chamber is removed from the influence ofsaid-temperature but is also provided with an orifice of small size. Byconnecting these two chambers with the samemeans for causi ing the flowof air through them, allirregu-` larities in the operation of such meansare compensated for inthe differential effect of the two pressures, sothat the instrument will measure the temperature in the pyrometricchamber, or, `more exactly, the difference between that temperature andthe atmospheric temperature to which thev balancin@ chamber issubjected.

y thekuse o f means for equating the capacity 'of the balancingchamber,and the 'resistance which it opposes totheflo-w v.of

air7 with the corresponding characteristics of the pyrometric chamber, ahigh degree of accuracy is attained, and it ismade practical to useregistering or indicating devices llocated at any desired distance fromthe furnace of which the temperature is to be measured.

In the accompanying drawings Fig. l represents, in a diagrammaticmanner, a pyrometric device embodying the present inven` tic-n, used tocontrol the temperature of a furnace. Fig. 2 shows a modification ofthemeans for actuating the controlling-valve, and Fig. 3 shows the use of avisual indicator in place of {control-mechanism.

In the embodiment of the invention shown Y in l the pyroineter isarranged to control the temperature of ka furnace 5. A

tube 6, made of suitable refractory material,

The balancing-chamber comprisesa tube j IO, also. fed with air through aperforated septum 1l, and is provided with a restricted outlet7 througha septum 12. This outlet may be adjusted by a needlenvalve 13. c

If the inlets to and the outlets from-,the tubes 6 and l() be of equalsize and the two tubes or chambers be at the same'temperature,thepressures within the two chambers, if they are both of smallvcapacity and length, will remain always the samevregardless of changesin the pressure of the air-supply. If, however, the chamber 6 be heatedbythe furnace, the air passing through this chamber will vbe heated andmore pressure will be requiredv to force a given mass of air through theseptum 7. The result will be a difference y -while the pressure in thepyrometric chamber will rise above oi fall below that in thebalancing-chamber as the temperature rises `above or falls below normal.

, i The indications o f the pyrometer are'reny g toward closed position;A fall in-the tem-v kdered efi'ective,inv the arrangement of'Fig. 1,

by connections, through pipes 14 and 15, to

kopposite sides of a chamber 16 which isdivided by a flexiblediaphragmvl?. HThisdiaphragm responds toV differences in the pressuresonitsv opposite surfaces, and it isuse'dl to control the heat ofthefurnace. For this purpose it is connected,through a suitable 1 mechanismv `18, with the feed-valve 19.

1through which gas is supplied to the burner `,20 by vwhich, the ffurnace is heated. "If lthe ktemperature of thefurnacerises abovenormalthe-pressure on the right-hand -side of parts. Where itisdesirable yto locate the respon the diaphragm exceeds, and thediaphragmmovesin a direction to move the valve 19 perature causes anoppositemovement of the sive device at a considerable distance lfrom thefurnace, and theeapacity-of the tube 6 is large .owing t'o its length,if this capacity preponderate `greatly overthat of the bal,-y

aneing-'charnber any changein the pressure of the air-supply willdisturb the balance between the 'pressures in the two chambers,

owing to the fact that the chamber of smaller capacityiwill respond"more quickly to the change. yWVhile. such disturbances will 'be 'use ofa receptacle 21 attached to the tube 10.

The size- 'fofthis receptacle is, 'of course, va-

only temporary theywill produce movements inthe responsive device whichmaybe undesirable, particularly inthev case `of a recording pyrometer. iAccordingly, I elimilnateffsuch disturbances by making the bal- "35.

ancing-chamber of' a capacity approximately equal: to that of thepyrometric chamber. In lfig; 1 this-is shown as accomplished by therie'dwith the length and `diameter of the tube 6.

yVVhere the length ofthe tube Gis great and its diameter is very smallin proportion, the

ressure `merel b reason of havin@V an equal capacity. To equalize thetwo chambers-in all respects it is desirable, therefore,

to make-their resistance to air-flow the same Avunderall"conditionsother than changes in temperature.

valves 22 andk 23 in the tube 10 on either side `Accordingly, Iintroduce of the capacity-receptacle 21, and a third valve 24between thetube and the receptacle. fby adjusting-these valves 'the effects ofre-.Ico

sista'nce'and vcapacity vinthe balancing-chamber 'may be :made: equal'to' those in thepyro- Vmetric chamber for all variations inthepressu-reef the airsupplyl `While the movement oftheresponsive dev lvice or diaphragm llf'inay be utilized; di?

vrectly, as inf -F ig.l,f'i"tl may; sometimes be desirable to use thisdevice merely as -a relay controlling` a motor ofl greater power. An

arrangement for-,this purpose is shown in. f

Fig. 2 where the diaphragm 17 moves an escape-valve 30 controlling anoutlet from .a

diaphragm-chanibei- 26 which is Vfed'with compressedair through a pipe27. Them air enters through aseptum 28 with ajrestri'cted opening,s'othat the pressure in the chamber varies as the valve 30 is vmoved tomore-'or less open position; A diaphragm 25, conspring 29'in aldirection to close the valve,

thebalancing-chamber.

ythe ypyrometric chamberrises above that in nect'ed to-the gas-valve19,A is pressed yby a and this willres'ult whenever the pressure in Inplace of or in addition. to 'the control.- Il ling functionabovedescribe'd, the pyronieter maybe 'used tooperate an indicatingorrecording instrumentality. A'simple form of indicating means forthispurpose is shown in Fig.'3,`where the pipes 1 4and'15 arecono nectedtothe ends of a glass UftubeBO 'con l taining mercury or other liquid 31.A suit- 2 yably graduated scale 32".may'indicate`tem perature's directlyVinA accordance with changes in the vlevel of the liquid. While l. l

this device willindicate alldepartures'of the temperature from'thefnormah its indications are only approximatexas tothe extent ofisuch variations,'since the ratiobetween 'thepressures lin the twochambersis not independent of the pressure oftheair-supply except .whenythis ratio is unity;` AneXact measurement of the ltemperature at anymoment can Abelob'- tained, however, by `adjusting"the valve 18 untilthe two pressures are balanced, and the position of thisvalvejwillthen'serve asv a direct indication of the temperature.

To avoid danger ofthe clogging of vth several restricted air-passages,it is desirable 'to introduce van air-filter y3 inthe supplypipe 8.

It'fwill be evident that the 'structural dej tails of theapparatus maybe greatly `*varied withoutk dep arture from the essence oftheinvention, of which thescopeand essentials are set forth in thefollowing claims. f f The invention claimedis': l n 1. A pyrometer'comprising: afchamber adjacentthe points of connection, the cham'- berbeing subjecteehnear one of said passages, tothe temperature to bemeasured; av

-connecting'tWo reg-ions of' different air-pre'ssures and provided vwithrestricted passages device responsive to variationsfof -thefpres- Y sureinthechain'ber between said fpassages and means for subjectingsaid"'dev`ice" to"` a changes'in the difference offpressure 'ini saidworegions."-` l .y l

2. `A pyrometer comprising two chambers,

force varying with and compensatingiforf4k each connecting two" regionsof Ydifferentlair-4 I pressures and provided with restrictedpas-1M'sages adjacent the points of connectiomfea'ch of the chambers beingsubjected to one of the two temperatures of which the dierence is to bemeasured: and a device responsive to variations in the relativepressures in said chambers between the` restricted passages therein. l

3. A pyrometer comprising: an elongated pyrometric chamber exposed, atits remote extremity, to a temperature to be measured, and provided,near both extremities, with restricted passages, said chamber connectingregions of different air pressures; a balancing-chamber connecting thesame regions of dii'lerent air-pressures and provided with restrictedpassages near its points of connection: means for substantiallyequalizing the air-capacity and resistance of the two chambers; and adevice responsive to variations in the relative pressures in saidchambers between the restricted pasages therein.

a. Ay pyrometer comprising: a chamber connecting two regions ofdilterent air-pressures, and provided with restricted passages adjacentthe points of connection, the chamber being subjected, near one of saidpassages, to the temperature to be measured; a heat-controlling deviceresponsive to variations o the pressure in the chamber between saidpassages: said device to a force varying with and compensating 'forchanges in the difference of pressure between said two regions.

and means for subjecting 5. A. pyrometer comprising: two chambers havinga common connection, through restricted passages, with a source ofcompressed air, each chamber having also a re-l strictedV outlet and one`chamber being subjected,between its inlet and its outlet, to thetemperature to be measured: and a device subjected, in oppositedirections, to the respective pressures in the two chambers and movablein response to dilerences between said pressures.

6. A pyrometer comprising: an elongated tubular pyrometric chambersubjected, near one extremity, to the temperature to be measured: arelatively short but equally capacious balancing-chamber; each of saidchambers being provided with restricted inlet and outlet openings; meansconnecting the inlets of the chambers with a common supply of compressedair; anda device subjected to the pressures in the two chambers andresponsive to dilierences therein.

7. A pyrometer, as set forth in claim 2, in which means are provided foradjusting at least one of said restricted passages independently of theothers.

8. A 'pyronieten as set forth in claim 5, in which means are providedfor adjusting the restricted outlet of that chamber which is notsubjected to the temperature to be measured.

IVAR LUND GAARD.

